The invention concerns a coated cemented carbide cutting insert that has a substrate with a porosity (per the ASTM Designation B 276-86, entitled "Standard Test Method for Apparent Porosity in Cemented Carbides") of greater than C00 and less than or equal to C04 wherein there is a zone of non-stratified, i.e., generally homogeneous, binder enrichment beginning near and extending inwardly from a peripheral surface of the substrate.
Heretofore, there has been the Kennametal KC850.RTM. coated cutting insert (KC850 is a registered trademark of Kennametal Inc., of Latrobe, Penn. 15650, USA, for cutting inserts) which has a C03/C05 porosity substrate which has a zone of surface binder enrichment. This binder enrichment is a stratified type of binder enrichment meaning that the binder enrichment forms in distinct layers of binder metal. The Nemeth et al. article, "The Microstructural Features and Cutting Performance of the High Edge Strength Kennametal Grade KC850," Proceedings of Tenth Plansee Seminar, Reutte, Tyrol, Austria, Metalwerke Plansee A.G. (1981), pp. 613-627, describes the "Kennametal KC850.RTM." coated cutting tool (or insert). The "Kennametal KC850.RTM." coated cutting insert has a tri-phase coating of TiC--TiCN--TiN, according to U.S. Pat. No. 4,035,541, to Smith et al., entitled "Sintered Cemented Carbide Body Coated with Three Layers."